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Patented June 15,1880.

Transmitter for Telephones.

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R. M. LOCKWOOD & SpH. BARTLETI.

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l UNITED STATES PATENT Erica.

ROBERT M. IOOKWOOD AND SAMUEL H. BARTLETT, OF NEW YORK, N. Y., ASSIGNORS OF ONE-HALF OF THEIR RIGHT TO CHARLES F. LIVERMORE,

OF SAME PLACE.

TRANSMITTER FOR TELEPHONES.

SPECIFICATION forming part of Letters Patent No. 228,824, dated June v15, 1880.

Application iled March 9, 1880.

To all whom t may concern Be it known that we, ROBERT M. Loox- WooD and SAMUEL H. BARTLETT, both of the city, county, and State of New York, have invented certain new and useful Improvements in Transmitters for Telephones or Vocal Telegraphs, of which the following is a full, clear, and exact description, reference being had to the accompanying drawing, which represents 1o oui` improved transmitter in section.

In the telephones as heretofore constructed the transmitting-instrument, or that which receives the sound-Waves and transmits them to the electrically-charged conductors, has been organized upon the theory of mechanical vibration due to the action of the sound-waves, and from this has arisen the device of a thin iiexible metallic diaphragm, the vibrations of which were transmitted by the electric current 2c to the receiver; and all telephones in what may be termed successful operation, in one form or another, so far as we are acquainted with them, employ this so-ealled mechanical vibration.77 We propose to dispense with this 2 5' mechanical Vibration, and asa substitute there for we employ what we term molecular disturbance or vibration, the construction of our apparatus being such as to prevent, as far as practicable, anything in the nature of mechanical vibration. This feature was partially developed in an application for Letters Patent tiled by us November 3, 1879; but in that the carbon plates,while supported by the non-resonant material, were left uncovered at their 3 5 inner adjacent ends, and sound-chambers were formed in the non-resonant block on opposite sides thereof, 011e of which communicated with the external atmosphere, rendering the plates and the connecting-button.liable to be more or 4o less affected or mechanically disturbed by the direct action of the sound-waves. In the present instance we embed the carbon or conducting plates solidly throughout their entire length in and cover or surround said plates 4 5 and the button with the non-resonant material,

as hereinafter explained. In the accompanying drawing, A represents a base-plate of wood, upon which is secured a block or cylinder, B, of cork or other suita- (No model.)

ble non-resonant material. Near the upper end of this block two bars or plates of carbon, b b', or other suitable conductors of electricity, are secured by being solidly embedded in the cork, as shown. These bars are arranged transversely of the block, extending from near irs center to or nearly to its outer face, on opposite sides, as shown. Between the inner adjacent ends of these bars is placed a headed pin of carbon or other suitable conducting material similar to that of which the bars are composed, the head of said pin constituting what we term. a button,7 which connects the two plates and rests upon the adjacent ends ot' the bars by its own gravity. A cavity is formed in the block B directly over this button, to give access to it for removing or replacing it, and this cavity, when the button is in place, is closed by a plug, B', of similar material to that of which the body of the block is formed, and which rests in close proximity with and prevents accidental displacement of the button. The block B thus formed, with the carbon bars embedded within it, is by preference fitted snugly in a metal cylinder, D, the open end of which rests against the base-plate A, the other end being covered by a metal cup or cover, D', screwed upon or otherwise firmly secured thereto, and the metal case is in turn covered with leather, rubber, canton-flannel, or other soft non-resonant material, as shown but the metal cylinder and its covering may be dispensed with.-

Wires e c are connected With the carbon plates b b', one to each, and extend thence out through the body B of the block in any convenient direction, and are connected at their outer ends to screw posts f f on the base-plate A. The main-line wires connected with the battery are also connected with these screwposts in the same manner as in an ordinary telegraph-instrument, and, as will be seen, the wires e e', carbon plates b b', and button b2 serve to connect said main -line Wires and thereby complete the circuit.

The sound-waves, in speaking, Ste., are re- 95 ceived upon the face or sides of the block of non-resonant material, or upon its covering described, and are communicated through said block and the carbon plates to the button b2, and through what We term a molecular disturbance7 the action or disturbance of the latter is communicated through the plates to the electrically-charged Wires c e', which complete the battery-circuit, and thence over the mainline Wires to the point connected therewith. We thus make use of the direct current from the battery in the transmission ofthe sound- Waves, and are thus enabled to transmit them like distances and with the same precision as an ordinary telegraphic message is transmitted.

As will be seen, our construction of the transmitter is such as is calculated to, and we believe it does as far as practicable, obviate all so-called mechanical vibration 'of the parts; for the carbon`or conducting bars or plates being solidly cushioned or embedded in some firm non-resonant substance, (such as cork,) the disturbance caused must be other than 'mechanical, and constitutes what we call moleculai` disturbance.

The means for repeating or transmitting the vocal sounds over long lines or a series of circuits and for receiving the same are embraced in other applications filed herewith7 and need not therefore be here described.

Having now described our invention, We claiml. In a transmitter for telephones or vocalsound telegraphs, a block of non-resonant substance provided with strips or plates or" carbon or other conducting material embedded in it, for the purpose and substantially as described.

' 2. The block of non-resonant material having` conductors embedded within. it, and Wires extending therefrom for connecting` them with the main-line current, substantially as described. Y

3. The non-resonant block in Which the carbon plates are embedded, in combination with the inclosing metallic case or cylinder, substantially as described.

4. The combination of the non resonant cover thereto, substantially as described.

RoBT. M. LooKWooD. SAMUEL H. BARTLETT.

W'itnesses:

F. L. OURAND, ALEX. MAHoN.

block B, inclosing metal ease D, and flexible 

